The scroll compressor has become a more widely used mechanism for home and business air conditioning in recent years. In a scroll compressor, two scroll elements having cooperating scroll wraps are moved relative to each other to compress a refrigerant from a suction pressure on the low pressure side of the compressor to a discharge pressure on the high pressure side of the compressor. When scroll compressors are shut down or have power interruptions, the high pressure discharge gas tries to equalize itself with the low pressure suction gas. This can cause the compressor to run in reverse until the pressures are in equilibrium. Reverse rotation causes objectionable noise and can cause a single phase compressor to actually run powered in reverse when a power flicker is encountered. A check valve has been utilized in the discharge passage of the scroll compressor to prevent this reverse rotation.
While adequate check valves exist, they generate undesirable noise during normal operation of the scroll compressor. For most of the conditions in a scroll compressor's operating envelope, the gas is either being over compressed, or worse, under compressed. When the compressor is running at an under compression condition, the check valve sees a powerful gas pressure and velocity reversal that tends to close the valve violently during each of these reversals. These reversals can occur at nearly sixty (60) times per second during normal operation. This generates undesirable check valve noise continuously during normal operation of the scroll compressor. A need exists to develop a check valve which operates quietly during normal operation, yet closes quickly during shutdown to prevent objectionable compressor shutdown noise.